Durable Infrastructure Research Articles

The East India Company and the island of Johanna (Anjouan) during the long eighteenth century

For just over 230 years the East India Company’s maritime operations were supported by a far-flung network of islands, ports and watering points across the Atlantic and Indian Oceans. These places provided supplies to company ships and safe havens in times of danger. The island of Johanna, or Anjouan, in the Mozambique Channel was one such place and this article considers how it came to be a key component within the company’s maritime system. The article also examines why the company chose not to exert direct control over the island when it had the opportunity to do so at the end of the eighteenth century. It is concluded that Johanna formed an important part of the flexible and durable maritime infrastructure that underpinned the territorial empire constructed by the company in India from 1750 onwards.

Eco-friendly self-compacting cement pastes incorporating wood waste as cement replacement: A feasibility study

Abstract This experimental study explores the feasibility of the development of eco-friendly self-compacting cementitious systems, utilizing wood waste sawdust (SD), for sustainable building construction. Two different gradations of SD viz-a-viz, coarse SD (CSD) and fine SD (FSD) were used in modifying neat Portland cement paste system as partial replacement of cement, in various weight fractions of 2%, 5%, and 7%. The fresh and hardened state properties of SD modified paste were determined. The results indicated that despite the strength reduction with SD addition in cement paste (strength decrease of 11%–34% was observed with SD addition), the resulting shrinkage strain is greatly reduced owing to the higher water absorption of SD particles thus increasing the water demand, to maintain self-compactibility, as well. The reduction in shrinkage of SD modified pastes was significant, with a reduction range of 45%–80%, as compared to control sample. Density and unit weight of the developed pastes were also reduced. The ability of SD to absorb water and releasing it later, thus providing moisture for cement hydration, suggests that SD has the potential to serve as an internal curing agent in self-compacting cementitious systems. Utilizing SD in cementitious binders may, then, not only promote sustainable development, but also lead to more durable infrastructures.

Distributed Agency Between 2D and 3D Representation of the Subsurface

Although severely altered, the urban subsurface is the base of the natural system, and is crucial for a stable, green, healthy, and liveable city. It is also the technical space, the engine room of the city where vital functions such as water, electricity, sewers, and drainage are located. This hybrid state needs to be recognized when designing resilient and durable (subsurface) infrastructure within urban renewal projects, so as to properly employ the parameters of both natural and technical systems. Interdisciplinary work is needed in order to be able to link natural systems (a) the water cycle, (b) soil and subsurface conditions, (c) soil improvement technology, and (d) opportunities for urban renewal (e.g. urban growth or shrinkage) in an efficient way. The importance of implementing “boundary spanning” when doing interdisciplinary work that deals with the effects of climate change is a widely recognized method, and has been an object of study in the city of Rotterdam in the past decade. The particular need for a “distributed agency” became clear during several research projects dealing with climate change, because it enables different actors to contribute to the development of the project at different phases. The representation of the city as both a natural and technical construction has been tested through the use of 2D and 3D information, which has played a significant role in enabling designs to incorporate the dimension of the subsurface. 2D and 3D information needs to anticipate different scales of specific planning and/or design phases, and they must also address various topics of the subsurface. For each phase of urban development, the distributed agency between 2D and 3D information is investigated and reflected upon. Conclusions are then drawn on the relationship between 2D and 3D information, and how it could relate in a productive, boundary spanning act that is inclusive of the subsurface. Based on these potential connections, the design of a new concept which implements boundary spanning as a facilitator is presented.

An Innovative Approach to Control Steel Reinforcement Corrosion by Self-Healing.

The corrosion of reinforced steel, and subsequent reinforced concrete degradation, is a major concern for infrastructure durability. New materials with specific, tailor-made properties or the establishment of optimum construction regimes are among the many approaches to improving civil structure performance. Ideally, novel materials would carry self-repairing or self-healing capacities, triggered in the event of detrimental influence and/or damage. Controlling or altering a material’s behavior at the nano-level would result in traditional materials with radically enhanced properties. Nevertheless, nanotechnology applications are still rare in construction, and would break new ground in engineering practice. An approach to controlling the corrosion-related degradation of reinforced concrete was designed as a synergetic action of electrochemistry, cement chemistry and nanotechnology. This contribution presents the concept of the approach, namely to simultaneously achieve steel corrosion resistance and improved bulk matrix properties. The technical background and challenges for the application of polymeric nanomaterials in the field are briefly outlined in view of this concept, which has the added value of self-healing. The credibility of the approach is discussed with reference to previously reported outcomes, and is illustrated via the results of the steel electrochemical responses and microscopic evaluations of the discussed materials.

Reassembling Caribbean Energy? Petrocaribe, (Post-)Plantation Sovereignty, and Caribbean Energy Futures

In this paper, we probe the possibilities and limits of Petrocaribe, a Venezuelan-led oil alliance that has shaped energy and development initiatives in the Caribbean basin since the mid 2000s, as well as U.S. responses to the program. Drawing from a range of sources, including interviews with regional actors and leaked diplomatic cables from Wikileaks, we describe some of the contours of these competing regional energy assemblages, and analyze how they intersect with both the legacies of colonial dependency and more recent neoliberal models for development within the Caribbean region. We contextualize and frame these initiatives by drawing from Caribbean scholarship on regional history and contemporary change and focus in particular on the continuing role of the plantation model in shaping regional affairs. We place this Caribbean scholarship in conversation with recent work in the social sciences utilizing the concept of assemblage that, we suggest, can be usefully adopted to trace how Caribbean energy networks and relations are structured and change over time. We argue that while Petrocaribe successfully provided opportunities for new forms of Caribbean development, the program had to be layered onto an already-existing oil assemblage comprised of durable infrastructures, private sector actors, and geopolitical interests, thus responding to conditions that limit the available options for truly transforming energy relations within the region. While such conditions opened up a space for a viable U.S. response to Petrocaribe, we argue that U.S. government initiatives in the region have consistently embraced a private sector approach that reproduces existing dependencies rather than enhancing the region’s energy sovereignty.

Differential Kelvin Probe Potential Mapping of Concrete for Reinforcing Steel Corrosion Assessment

Chloride induced corrosion of steel reinforcement in concrete seriously limits civil infrastructure durability. Chloride ion intrusion through the concrete cover causes local passivity breakdown of the embedded reinforcement. Activation of the steel is manifested by a local open circuit potential drop reflecting increased polarization of the cathodic reaction , usually oxygen reduction, to match the increase in anodic current density. Local potential can be measured using a conventional Copper/Copper Sulfate reference electrode (CSE) with its wet junction tip physically contacting the external concrete surface at points on a grid pattern. The metallic terminal of the CSE is connected to the negative terminal of a high input impedance potential meter; the other terminal of the potential meter is connected to a point of the normally interconnected reinforcing steel (rebar) assembly, reached through a hole drilled in the reinforced concrete. The potentials measured at the grid are mapped revealing the locations of more negative readings, thus providing a diagnostic indication of where corrosion is occurring so local remedial action can be taken on an informed basis. While very useful, this type of survey can be time consuming. Delays occur because adequate contact between the moist CSE tip and the electrolyte in the concrete pore network may require some form of moisturizing surface preparation, and some time for stabilization of diffusional potentials that were altered by intrusion of newly introduced electrolyte in the pore network near the concrete surface. Such delays can become prohibitive in surveys that involve hundreds or thousands of m2 of highway bridge deck, especially if it becomes necessary to temporarily close traffic lanes. A radically new approach to conduct surface potential surveys in reinforced concrete uses a scanning array of mobile, macroscopic Kelvin probes. The Kelvin Probe (KP) uses a vibrating metallic capacitor disk hovering, but not touching, close to the concrete surface. In a metallic disk - metal surface system the KP yields the value of the difference of the Volta potential of both surfaces, obtained by finding the value of the potential difference that need to be applied in a connecting disk-metal surface circuit to null out the capacitive alternating current that would otherwise circulate there. On concrete, the probe provides the difference between the Volta potential of the metallic disk and an averaged, effective Volta potential of the heterogeneous concrete surface beneath the disk footprint. Because no surface preparation or electrolyte exchange is needed, the KP provides nearly instantaneous readings and obviates the need for stabilization delays thus opening the way for fast and practical surveying of large structures. Recent investigations [1, 2] have shown that the surface potential map obtained with an appropriately scaled macroscopic KP successfully reproduced the key features of the maps obtained with the conventional method, indicating that the spatial variations in the effective Volta potential of the concrete (and identification of corroding regions) can be used instead of those provided by the CSE survey, but at a much faster scanning speed. Until now KP operation was demonstrated only with wired contact to the rebar assembly. This investigation examines a differential mode, where anode identification is made without need for a trailing wire rebar contact, Potential measurements used a scanning array of two KPs 0.4 m from each other with galvanized steel sensing disks 0.1 m in diameter placed 0.01 m above the surface of an ~2.4x2.4 m reinforced concrete slab. The probes operated at a vibrating frequency of ~0.15 kHz with vibration amplitude > 1mm. The steel reinforcement in the slab was segmentally polarized via externally impressed currents to create temporarily anodic regions ~ 0.2x0.6 m on the external concrete surface. Differential operation was achieved over the entire concrete grid by means of an auxiliary temporary reference electrode that established periodic contact with the concrete surface, but serving only as a provisional link between contactless KP measurements thus keeping the overall scheme referenced to the metal disks. The results confirmed the suitability of the differential operation scheme and were contrasted against results of replicating conventional electrode measurements. Implications on deployment of this technique in highway applications and extension to larger KP arrays are discussed and presented. [1] Sagüés. A. and Walsh, M. “Kelvin Probe electrode for contactless potential measurement on concrete – Properties and corrosion profiling application”, Corrosion Science, Vol 56, pp 26-35, 2012. [2] Sagüés. A. and Emmenegger, L. “Contactless Electrode for Fast Survey of Concrete Reinforcement Corrosion” Final report, NCHRP IDEA Project 176, Transportation Research Board, National Research Council, Washington, DC, 2017 (In Press).

Mechanical characterization of auxetic stainless steel thin sheets with reentrant structure

Smart materials in auxetic form present a great potential for various medical applications due to their unique deformation mechanisms along with durable infrastructure. Both analytical and finite element (FE) models are extensively used in literature to characterize mechanical response of auxetic structures but these structures are mostly thick enough to be considered as bulk material and 3D inherently. Auxetic plates in very thin form, a.e. foil, may bring numerous advantages such as very light design and better biodegradability when needed. However, there is a gap in literature on mechanical characterization of auxetic thin plates. In this study, structural analysis of very thin auxetic plates under uniaxial loading is investigated using both FE method and experimental method. 25 μm thick stainless steel (316L) plates are fabricated with reentrant texture for three different unit cell dimensions and tested under uniaxial loading using universal testing machine. 25 and 50 μm thick sheets with same cell dimensions were analyzed using implicit transient FE model including strain hardening and failure behaviors. FE results cover all the deformation schemes seen in actual tests and total deformation level matches with test results. Effect of plate thickness and cell geometry on auxetic behavior is discussed in detail using FE results. Finally, based on FE analysis results, an optimum geometry for prolonged auxetic behavior, high flexibility and high durability is suggested for future potential applications.

Influence of Random Inclusion of Synthetic Wicks Fibers of Hair on the Behavior of Clayey Soils

Several soil improvement methods are used to enhance the engineering properties of soil, among which, reinforcement by fibers is considered as an effective ground improvement method because of its cost effectiveness, and easy adaptability. The present investigation chooses synthetic wick and vinifera raphia fibers as reinforcement. The synthetic wick fiber was randomly included into the soil at four different percentages i.e. 0, 2, 4, 6% by volume of raw soil. Vinifera raphia fiber was used at one percentage (4%) as control. The main objective of this research is to focus on the strength behavior of clayey soil reinforced with randomly included synthetic wick fiber. The physical and mineralogical characterization was carried out on ten soil samples. The compression, flexion, abrasion, water absorption and capillarity tests were performed on synthetic wick reinforced specimens with various fiber contents. The results of these tests have clearly shown an improvement in the compression strength values from 1.65 to 2.84 MPa for the wicks fibers, and the flexural strength values which varied between 1.08 and 1.96 MPa. Hence, the waste of synthetic wick fibers is therefore an efficient reinforcement for compressed earth blocks, which are very significant for construction of durable and economic infrastructures.

Stabilization of Fine-Grained Soils Against Desiccation Cracking Using Sustainable Materials

Abstract Desiccation cracking is a phenomenon commonly associated with the fine-grained soils, which initiates at their surface and subsequently propagates deeper inside their matrix. Hence, for safe and durable infrastructure development, stabilization of such soils becomes important. In order to stabilize these soils, cement, chemicals, and fibers have been employed by earlier researchers. However, in recent times, the ill effects of these stabilizers on the ecosystem have been realized, and hence their replacement with sustainable materials that are mostly industrial by-products is becoming necessary. This philosophy would not only conserve natural resources, but would also result in a “marriage” between “two suitable” materials to create a “synergy” within the ecosystem. With this in view, the ground granulated blast furnace slag (GGBS), a by-product from the iron and steel plants, was activated by red mud (RM), a by-product from alumina manufacturing units, with an objective to establish its utility in stabilizing the fine-grained soils against desiccation cracking. To achieve this, the parameter crack intensity factor (CIF), which has been employed by earlier researchers to quantify cracking characteristics of the (virgin) soil mass, has been employed for the soils amended with GGBS and RM. Subsequently, the CIF has been correlated with the soil specific parameters (viz., cation exchange capacity and tensile strength) and the environmental conditions (viz., humidity and temperature), represented by the evaporation rate of the soil mass. Based on these extensive investigations, it has been demonstrated that such correlations would be very useful for selection of the right combination of the soil and sustainable material(s) to achieve a stabilized system of the fine-grained soil. It has been put forth through this study that the by-products chosen exhibit high potential to stabilize the fine-grained soils, which also resulted in alteration of their micro-structure and strength post stabilization. Furthermore, studies have been carried out to establish the effect of addition of industrial by-products to virgin soils, mainly in terms of their micro-structure, which in turn controls their strength.

Open-source mobile digital platform for clinical trial data collection in low-resource settings

BackgroundGovernments, universities and pan-African research networks are building durable infrastructure and capabilities for biomedical research in Africa. This offers the opportunity to adopt from the outset innovative approaches and technologies...

Life Cycle Cost Evaluation of Noise and Vibration Control Methods at Urban Railway Turnouts

A focus of the railway industry over the past decades has been to research, find and develop methods to mitigate noise and vibration resulting from wheel/rail contact along track infrastructure. This resulted in a wide range of abatement measures that are available for today’s engineers. The suitability of each method must be analysed through budget and timeframe limitations, which includes building, maintenance and inspection costs and time allocation, while also aiming at delivering other benefits, such as environmental impact and durability of infrastructure. There are several situations that need noise and vibration mitigation methods, but each design allocates different priorities on a case-by-case basis. Traditionally, the disturbance caused by railways to the community are generated by wheel/rail contact sound radiation that is expressed in different ways, depending on the movement of the rolling stock and track alignment, such as rolling noise, impact noise and curve noise. More specifically, in special trackworks such as turnouts (or called “switches and crossings”), there are two types of noise that can often be observed: impact noise and screeching noise. With respect to the screeching (or flanging), its mitigation methods are usually associated with curve lubrications. In contrast, the impact noise emerges from the sound made by the rolling stock moving through joints and discontinuities (i.e., gaps), resulting in various noise abatement features to minimise such noise impact. Life cycle analysis is therefore vital for cost efficiency benchmarking of the mitigation methods. The evaluation is based on available data from open literature and the total costs were estimated from valid industry reports to maintain coherency. A 50-year period for a life cycle analysis is chosen for this study. As for the general parameters, an area with a high density of people is considered to estimate the values for a community with very strict limits for noise and vibration.

Preliminary Assessment of Durability of Sustainable RC Structures with Mixed-In Seawater and Stainless Steel Reinforcement

The massive use of natural resources such as fresh water or virgin rock for aggregates in the construction industry originates the need for possible alternative solutions aimed at the environmental sustainability, as, for instance, the use of chloride-contaminated raw materials for the production of concrete. In the framework of a research project financed by the Infravation Program (Advanced systems, materials and techniques for next generation infrastructure), an experimental study is undertaken aiming at demonstrating the safe utilization of seawater and salt-contaminated aggregates (natural or recycled) for a sustainable concrete production when combined with non-corrosive reinforcement to construct durable and economical concrete infrastructures. Considering the lack of sufficient fresh water in many regions of the world, this paper focuses on a preliminary evaluation of the possibility of replacing fresh water used to mix/cure concrete with seawater, combined with different types of stainless steel reinforcement. Based on literature data and the performance-based approach of “Model Code for Service Life Design” published by the International Federation for Structural Concrete (fib), risks associated with the use of using seawater in relation to the service life a reinforced concrete element in a marine environment are investigated. During the development of the project, laboratory and field tests will allow for the collection of experimental data to better define the durability evaluation and analyse advantages of the proposed approach in terms of life cycle assessment.

The durability and fragility of knowledge infrastructures: Lessons learned from astronomy

ABSTRACTInfrastructures are not inherently durable or fragile, yet all are fragile over the long term. Durability requires care and maintenance of individual components and the links between them. Astronomy is an ideal domain in which to study knowledge infrastructures, due to its long history, transparency, and accumulation of observational data over a period of centuries. Research reported here draws upon a long‐term study of scientific data practices to ask questions about the durability and fragility of infrastructures for data in astronomy. Methods include interviews, ethnography, and document analysis. As astronomy has become a digital science, the community has invested in shared instruments, data standards, digital archives, metadata and discovery services, and other relatively durable infrastructure components. Several features of data practices in astronomy contribute to the fragility of that infrastructure. These include different archiving practices between ground‐ and space‐based missions, between sky surveys and investigator‐led projects, and between observational and simulated data. Infrastructure components are tightly coupled, based on international agreements. However, the durability of these infrastructures relies on much invisible work – cataloging, metadata, and other labor conducted by information professionals. Continual investments in care and maintenance of the human and technical components of these infrastructures are necessary for sustainability.

The fourth pillar of infrastructure sustainability: tailoring civil infrastructure to social context

This research proposes technical performance over time as a fourth pillar of sustainability theory for infrastructure. It also describes a method that allows us to discover how changes in the technical pillar (operationalized as reduced breakage rates) may moderate the influence of the social pillar (operationalized as repair rates) on sanitation infrastructure outcomes. Oral histories were used to develop a history of sanitation for each of 152 poor households in four rural communities in Bangladesh that have gained access to sanitation in the past decade. Transcriptions and qualitative coding identified reported states of sanitation (for example, broken vs. functional) at three time steps. These were used to develop an initial vector and transition matrix for a Markov chain analysis. The breakage rate in this model was then adjusted to investigate the impact of improved technical durability on sanitation outcomes. For the case analysed here, we found that increasing infrastructure durability by 50% (an estimated increase of two years) increased the rate of functional sanitation system use at model convergence from 54% to 88%. Increases in durability also caused households to use private rather than shared systems. Beyond this specific case, the generalizable theory and method presented here are analytic tools that permit targeted technical accommodation of social contexts specific to individual project sites.

Characterization of macrocrack propagation under sustained loading in steel fibre reinforced concrete

Preoccupation for improving concrete infrastructure durability has become just as important as safety issues and concrete cracking plays a key role for durability. Despite various studies carried out in the last decade, very little information regarding the propagation of cracking under sustained loading and the physical mechanisms involved is available. In order to address this problem, an experimental study on the propagation of a macrocrack under sustained loading in steel fibre reinforced concrete (SFRC) beams was completed. This article describes the flexural creep tests carried out on 0.7 m long beams. The evolution of the deflection, the crack width and the crack propagation were measured until the specimens’ failure. The results permit the assessment of the influence of initial CMOD and sustained load levels on crack propagation, damage evolution, and the mechanisms leading to the rupture of the beams. In addition, behaviour of beams in sealed and drying hydric conditions with an identical loading history are compared to determine the influence of hydric conditions. The results show that crack propagation governs the failure mechanisms of SFRC beams subjected to high sustained load levels.

Deterioration of dynamic mechanical property of concrete with mineral admixtures under fatigue loading

The dynamic mechanical property of concrete is one of the key parameters, which greatly influences durability of infrastructures subjected to continuous heavy loading, such as girder and track slab of high-speed railway foundation structure. This paper reports serials of experiments designed to investigate the deterioration of dynamic mechanical properties of different concretes under fatigue loading condition. Four parameters including relative dynamic elastic modulus (RDEM), relative dynamic shear modulus (RDSM), relative compressive strength (RCS) and water absorption (WA) of concrete were evaluated to assess the dynamic properties and microstructures of concretes. Results show that the fatigue stress levels and fatigue cycle durations significantly influence the dynamic mechanical properties of concrete including dynamic elastic modulus and dynamic shear modulus. Addition of proper mineral admixture can improve the dynamic mechanical characteristics of concrete and increase its resistance against the fatigue loading effect. Keeping the amount of mineral admixture in concrete constant, its dynamic mechanical property with fly ash is lower than that with fly ash and silica fume. The water absorption in concrete, which is an indirect parameter reflecting capillary porosity, increases evidently after bearing fatigue-loading. There is a close correlation between the deterioration of dynamic mechanical property and the increasing of water absorption of concrete. This indicates that the damage of microstructure of concrete subjected to fatigue loading is the indispensable reason for the decay of its dynamic mechanical performance.

UK airfield pavement design using French asphalts

The requirement to build durable, sustainable and low-maintenance airfield infrastructures has become more important in recent years due to the expected air traffic increase and its impact on the environment. The high customer expectation of infrastructure availability and minimum traffic delay during maintenance has also become significant. This paper introduces French asphalt mix design methods for use in airfield pavement construction as an alternative to conventional UK materials, to offer improved performance and better whole-life cost solution. A case study at Sumburgh Airport in the Shetland Islands, UK is presented.

Shear deformations in calcium silicate hydrates

The calcium silicate hydrate (C–S–H) gel is the phase that provides cohesive strength to cement. The mechanics of the C–S–H gel at the molecular level is key to the durability of infrastructures made of concrete, controlling for example their macroscopic creep and shrinkage. The existing experimental techniques cannot access the nanostructure and properties of this very heterogeneous phase, and therefore atomistic simulations constitute a valuable alternative. Here we consider two established model systems for the solid part of the C–S–H gel that are representative of perfectly ordered and very disordered molecular structures: crystal tobermorite and glassy C–S–H. Using reactive force field simulations, we calculate elastic properties that match with experimental values from the literature. The analysis of the large deformations under shear indicates that the shear strain localizes preferentially at nanoscale sites that are rich in highly confined water. Implications of our findings for a colloidal description of the C–S–H gel mechanics and for the macroscopic properties of cement are finally discussed.

Addressing Infrastructure Durability and Sustainability by Self Healing Mechanisms - Recent Advances in Self Healing Concrete and Asphalt

Infrastructures cover a very broad spectrum of different materials. This paper focuses on civil engineering structures, concrete and asphalt in particular. The public demand for such infrastructures is high level of service and performance, high durability and minimum negative ecological impact. New emerging self healing materials science provides solutions to the problem. An overview is given of new developments obtained in research on self healing of cracks in cement based materials and asphalt concrete. At Delft University various projects are running to study self healing mechanisms. The first project that is discussed is Bacterial Concrete, in which bacteria are mixed in concrete, that can precipitate calcite in a crack and with that make concrete structures water tight and enhance durability. In a second project hybrid fibre reinforced cementitious materials are studied that can mechanically repair cracks when they occur. The last project described in this paper is on the ravelling of porous asphalt concrete and how to heal this damage by incorporating embedded microcapsules or steel fibres. The state of the art results in all projects show that self healing is not just a miracle, but materials can be designed for it.

Freeze-thaw influence on the flexural properties of ductile fiber-reinforced cementitious composites (DFRCCs) for durable infrastructures

Abstract Ductile fiber-reinforced cementitious composites (DFRCCs) are innovative cementitious materials characterized by multiple cracking and pseudo strain-hardening behavior under static flexure . This paper investigates the effects of freeze-thaw cycles, and water-to-binder ratio (W/B) as well as reinforcing fiber combination on flexural properties and cracking procedure of DFRCC prismatic specimens. The DFRCC materials used in the present study are reinforced with hybrid polyvinyl alcohol (PVA) and ultra-high molecular weight polyethylene (PE) at the 1.5% volume fraction. These DFRCC materials were tested for modulus of rupture (MOR), relative dynamic modulus of elasticity, and change in mass. The test results for freezing and thawing actions within 300 cycles indicate that freeze-thaw cycles have little effect on the MOR of the DFRCC materials, whereas freeze-thaw cycles have a negative effect on multiple cracking behavior and deformation capacity of DFRCC prismatic specimens under flexural loadings. The results of durability tests show that the DFRCC specimens remain durable after 300 cycles of freezing and thawing actions.